Roller fuser system with fusing member temperature control for printing

Abstract

Internally-heated external rollers transfer heat rapidly to a fuser roller in an electrostatographic printer. Stored media process set points, input image content and input media type data are used to regulate the heat transfer rate by varying the nip width between the heated external rollers and the fuser roller. The rate of heat transfer and the rate of heat transfer adjustment are sufficiently rapid that many different media weights and types may be mixed in a print run without restrictions on media run lengths, without collation requirements per run, and without productivity losses due to slowing of feed rate for heavier receivers.

1. An electrostatographic printer with a roller fusing apparatus comprising:
 a heated fusing member for fusing toner to sheets of receiver media; 
 one or more external heating members in heat transfer contact with said heated fusing member; 
 one or more external heat sink members in heat transfer contact with said heated fusing member; 
 a pressure member in contact with said heated fusing member to form a fusing nip there between; 
 a machine controller for changing fusing nip widths in accordance with the type of receiver media and the image on the media; 
 a heating member contact controller associated with said machine controller, for changing contact width between said external heating members and said heated fusing member; 
 a heat sink contact controller associated with said machine controller, for changing contact width between said external heat sink members and said heated fusing member;
 and a pressure member nip controller associated with said machine controller, for changing nip width between said pressure member and said heated fusing member. 
 
 
   
   
     2. The apparatus of  claim 1 , wherein one or more external heating members are rollers, which contain one or more internal heating sources. 
   
   
     3. The apparatus of  claim 2 , wherein one or more internal heating sources are each independently controlled by said machine controller. 
   
   
     4. The apparatus of  claim 1 , wherein one or more external heating members and said external heat sink members are independent heat transfer rollers, each independently controlled by said machine controller. 
   
   
     5. The apparatus of  claim 4 , wherein said heated fusing member is controlled by said machine controller in conjunction with said heating member contact controllers and said heat sink contact controllers to adjust one or more of said heat transfer rollers in response to temperature of said heated fusing member. 
   
   
     6. The apparatus of  claim 1 , further comprising air knives to emit air streams at an air flow rate for stripping receiver media with fused toner from said heated fusing member and said pressure member wherein said airflow rate is controlled by said machine controller. 
   
   
     7. A method for fusing toner to sheets of receiver media in an electrostatographic printer, comprising for each arriving sheet of receiver media the steps of:
 a. providing first data signals representative of characteristics of one or more of sheets of receiver media including a particular sheet of arriving receiver media; 
 b. providing second data signals representative of toner density for an image on said particular sheet of arriving receiver media; 
 c. providing third data signals representative of a fuser member comprising a fuser member temperature so that a selection can be made corresponding to one of said first, second or third data signals; 
 d. selectively heating said fuser member to bring said fuser member to a desired temperature for heat transfer of toner to a receiver media in accordance with at least one of said first, second or third data signals; 
 e. selectively adjusting pressure between a receiver media and said fuser member in accordance with one of said first, second or third data signals; 
 f. fusing the toner to the sheet of receiver media by said fuser member in contact with one or more external heat transfer rollers wherein a nip width between said external heat transfer rollers and said fuser member is adjusted to vary the amount of heat transfer between said external heat transfer rollers and said fuser member. 
 
   
   
     8. The method of  claim 7 , further comprising repeating steps a, b and c as required. 
   
   
     9. The method of  claim 7  further comprising repeating steps a, b and c as required during an interframe interval, before the arrival of each sheet of receiver media. 
   
   
     10. The method of  claim 7 , wherein said fusing step
 further comprises fusing the toner to the sheet of receiver media by said fusing member in contact with one or more heat sink rollers wherein said nip width between said heat sink rollers and said fuser member is adjusted to vary heat transferred from said fuser member to said heat sink rollers. 
 
   
   
     11. The method of  claim 7 , wherein said third data signal representative of a member temperature includes at least one of a temperature of an interframe, said heated fuser member, an external roller, and a fuser roller. 
   
   
     12. The method of  claim 7 , wherein said third data signal representative of a member temperature includes at least one of a temperature of said external heater roller, a heat sink roller, an airflow rate and an external roller internal heat source, and said fuser member. 
   
   
     13. The method of  claim 7 , further comprising performing step c to determine said third data signal by sampling at least one of a lengthwise temperate and a circumferential temperature. 
   
   
     14. A method for fusing toner to sheets of receiver media in an electrostatographic printer, comprising for each arriving sheet of receiver media the steps of:
 a. providing first data signals representative of characteristics of one or more of sheets of receiver media including a particular sheet of arriving receiver media; 
 b. providing second data signals representative of toner density for an image on said particular sheet of arriving receiver media; 
 c. providing third data signals representative of an interframe temperature so that a selection can be made of corresponding to at least one of said first or second data signals; 
 d. selectively heating a fusing member to bring said fusing member to a desired temperature for heat transfer of toner to a receiver media in accordance with at least one of said first or second data signals; 
 e. selectively adjusting pressure between a receiver media and said fusing member in accordance with at least one of said first or second data signals; 
 f. fusing the toner to the sheet of receiver media by said fusing member in contact with one or more extemal heat transfer rollers wherein a nip width between said external heat transfer rollers and said fusing member is adjusted to vary heat transferred between said external heat transfer rollers and said fusing member. 
 
   
   
     15. The method of  claim 14 , wherein said third data signal representative of a member temperature includes at least one of a temperature of said external heater roller, a heat sink roller, an airflow rate and an external roller internal heat source, and said fusing member. 
   
   
     16. The method of  claim 14 , further comprising performing step c to determine the third data signal by sampling at least one of a lengthwise temperate and a circumferential temperature. 
   
   
     17. The method of  claim 14 , wherein one or more external rollers are engaged to make temperature uniform based on a reading from said interframe area. 
   
   
     18. The method of  claim 14 , wherein an airflow is controlled to make the temperature uniform based on a reading from said interframe area. 
   
   
     19. The method of  claim 14 , wherein the fusing member temperature is adjusted to be uniformly homogeneous both in the lengthwise temperate and a circumferential temperature based on a reading from said interframe area.